What is the best way to quit smoking without falling back; do you cut down gradually or do you go cold turkey? Even experts disagree, and as it now seems, rightly so. The Biometris group of Wageningen University, together with psychologists from the University of Amsterdam, has formulated a mathematical model for smoking cessation. Within the model an optimal strategy can be found. The model distinguishes three factors, the nicotine level in the body, the desire to light another one, and the will not to. Eventually the will must overcome the desire. Within the model it appears,

the probability for success is maximal for a combined strategy; start cutting down gradually and quit fully at the right time. Still the best strategy is to never start smoking.

Nicotine addiction is a relatively simple process. The nicotine that enters the body when smoking activates receptors in the brain. These in turn stimulate the activity of dopamine, a so called neurotransmitter, which makes you feel good. If the nicotine level drops, the activity of dopamine decreases. Because your body has become used to the higher activity level, you feel the desire to resume smoking. The circle closes; the question is how to break it. The point is that the nicotine in your body is broken down within a day or so, but the craving for a cigarette remains for months. Simply stated, the battle is between the will to stop and the desire to continue; it is mind against body. That is the real problem.

The will to stop smoking, a factor that within the model is called self or societal control, is influenced by many aspects; the notion that smoking is bad not only for your own health but also that of the people around you, the social acceptance of smoking, the price of sigarettes, smoking bans in public places, they all play a role. The importance of all these aspects differs from person to person. A therapy for smoking cessation should not only address the reduction of the craving, stimulating the will to stop is at least as important The mathematical model distinguishes three factors, the nicotine level in the body, the craving for smoking and the will to quit. These factors influence one another in such a way that two stable states occur, that of the regular smoker and that of the total abstainer. It appears there is no intermediate, not within the model at least. In practice that may well be the same, considering the problems so called “casual” smokers encounter when they want to quit. What may happen is that a smoker is at a pivotal point, where just a small push can suffice to quit smoking once and for all.

Exactly that is what the model describes. By gradually cutting down the daily nicotine intake, a smoker is driven towards that pivotal point. Once there it is relatively easy to stop smoking completely, without the chance of falling back in the habit, given that extra push. Just realising that you actually can survive a day without a single cigarette, or experiencing the rich taste of food or the intense smell of flowers can provide that incentive, each person will have her or his own experience. Obviously a mathematical model can not determine that, but it does tell us there is such a pivotal moment.

Of course it is only a model still; the important message is that the model indicates that a combined therapy could be the optimal one. Probably the smoker will feel when it is the right time to fully stop, the model says that indeed there is such a moment, and that supports the feeling. The mathematical model is developed for nicotine addiction; unfortunately the conclusions do not apply straightforwardly for any kind of addiction. These same three factors, physical processes, the craving to continue and the will to stop smoking will apply in other cases, but their interplay and whether that leads to a similar model remains an open question. Mathematicians can help answer such questions when

they collaborate with psychologists. That too is an important message.

The model conflicts with studies showing that cold turkey is generally twice as effect as gradual weaning or stepped-down tapering schemes (see http://www.ncbi.nlm.nih.gov/pubmed/17654293 ). This is rather important when you consider that more smokers quit cold turkey than by all other methods combined (see http://www.ncbi.nlm.nih.gov/pubmed/16137834 ). I mean why would we want to make withdrawal last one second longer than necessary?

Successful nicotine dependency recovery really only has one rule, that one equals all, that lapse equals relapse, that one puff of nicotine will always be too many while thousands are never enough. Yep, just one rule that if followed provides 100 percent odds of success … no nicotine today!

question is could this model be used for quitting other drugs as well?